Recently, various transition metal complexes constituted of transition metal species and ligands have been used as catalysts for organic synthesis reactions. As a factor for the expression of the performance or activity of such a catalyst, it is well known that not only the transition metal species but also the ligand plays an important role in a metal complex. For this reason, numerous compounds having coordinating nature, including phosphorus compounds, have been developed as ligands so far. Moreover, for organic synthesis reactions catalyzed by metal complexes, optimum catalysts for a wide variety of reactants can be prepared by appropriately combining a transition metal species and a ligand. Hence, the research and development of such organic synthesis reactions catalyzed by metal complexes are still being actively carried out. For putting a catalytic organic synthesis reaction into an industrial use, the variety of ligands greatly contributes to the optimization and efficiency improvement of the reaction, because the number of transition metals is limited. Actually, however, even with the use of ligands developed so far, the catalytic activity and the reaction selectivity are insufficient in some reactions. Even if the performance of a ligand is extremely efficient, it is difficult to apply the ligand to an industrial catalytic organic synthesis reaction, unless the ligand can be mass produced easily at low costs. From the above-described viewpoints, the development of a novel phosphorus compound which can be mass produced easily at low costs and which can be used as an efficient ligand is still eagerly awaited under the current situation.
An example of the phosphorus compounds is the N-(2-phosphinophenyl)carbazole represented by the following general formula (2), where R represents an alkyl group or an aryl group, developed by Fuk Yee Kwong et al. (Sheung Chun and Fuk Yee Kwong, “Highly efficient carbazolyl-derived phosphine ligands: applications to sterically hindered biaryl couplings”, Chemical Communications, 2011, 47, 5079). Reportedly, this phosphorus compound works as an extremely efficient ligand in a cross-coupling reaction between an aryl halide and an arylboronic acid catalyzed by palladium, which is one of the transition metals (that is, the Suzuki-Miyaura coupling reaction). However, the synthesis of the phosphorus compound inevitably involves the Ullmann reaction which requires high temperature and long time, and which is poor in reaction selectivity and isolated yield, and the halogen-lithium exchange and the phosphination reaction which require extremely low-temperature. For this reason, it is extremely difficult to mass produce this phosphorus compound at low costs.
